Drilling in the earth is commonly effected by forcing a drill having a plurality of drill bits, each holding a plurality of cones set at outward angles, through the earth formations, essentially crushing the formations. The drill bit cones rotate on their axes and are in turn rotated about the drill bit main axis, which can be the axis of a drill string in oil field drilling for example.
Drill bit cones are typically high strength alloy steel shaped into approximately conical configurations, provided with bearings and rollers and mounting a plurality of inserts, typically tungsten carbide inserts, which are usually soldered into preformed pockets distributed circumferentially around the bit cone body, the inserts being of sufficient length to project from the bit cone body a distance to maximize the crushing forces on the earth formation surrounding the drill bit.